Dielectric-layer-coated substrate and installation for production thereof

ABSTRACT

The invention relates to a substrate ( 1 ), especially a glass substrate, coated with at least one dielectric thin-film layer deposited by sputtering, especially magnetically enhanced sputtering and preferably reactive sputtering in the presence of oxygen and/or nitrogen, with exposure to at least one ion beam ( 3 ) coming from an ion source ( 4 ), characterized in that said dielectric layer exposed to the ion beam is crystallized.

The present invention relates to the field of dielectric-based thin-filmcoatings, especially of the metal oxide, nitride or oxynitride type,which are deposited on transparent substrates, especially glasssubstrates, using a vacuum deposition technique.

The invention relates to a coated substrate, to a manufacturing process,to an installation for manufacturing and for applying the substrateand/or the process for producing glazing assemblies, especiallydouble-glazing or laminated glazing assemblies, comprising at least onesubstrate according to the invention.

For the purpose of manufacturing what are called “functional” glazingassemblies, the usual practice is to deposit, on at least one of thesubstrates of which they are composed, a thin-film layer or a thin-filmmultilayer, so as to give the glazing assemblies optical (for exampleantireflection) properties, properties in the infrared (low emissivity)and/or electrical conduction properties. Layers based on an oxide and/ornitride dielectric are frequently used, for example on either side of asilver layer or a doped metal oxide layer, or as an interferential layerin multilayers in which low- and high-refractive index dielectricsalternate.

Layers deposited by sputtering are reputed to be somewhat lesschemically and mechanically resistant than layers deposited bypyrolithic deposition. Thus, the experimental technique ofion-beam-assisted deposition has been developed in which a layer isbombarded with an ion beam, for example an oxygen or argon ion beam,which makes it possible to increase the density of the layer and itsadhesion to the carrier substrate. This technique has for a long timebeen applicable only to very small sized substrates, owing to theproblems posed in particular in terms of convergence between, on the onehand, the ion beam coming from a very localized source and, on the otherhand, the particles resulting from the evaporation or sputtering of thetarget.

Document EP 601 928 discloses a sequential treatment of the depositedlayer, by firstly depositing a layer in a sputtering chamber and thenbombarding this dielectric layer after it has been deposited with a “lowenergy” ion beam coming from a point source, with an energy allowing thesputtering of the layer under the impact of the ions of the beam to belimited, typically of less than 500 eV and around one hundred eV.

This treatment is aimed essentially at increasing the physical and/orchemical durability of the layer, by densification of the layer, andmakes it possible to achieve a lower surface roughness of the layer,favoring the subsequent “layering” of a layer subsequently deposited ontop of it.

However, this treatment has the drawback of only being able to becarried out on a fully deposited layer.

Another drawback of this treatment is that it allows only densificationof the layer thus treated and this densification causes an increase inthe refractive index of the layer thus treated. The layers thus treatedtherefore cannot replace the untreated layers, because of theirdifferent optical properties, and mean that the multilayer systems, inwhich the material must be included, have to be completely redefined.

In addition, this treatment is not optimized for being carried out on alarge substrate, for example for the production of an architecturalglazing assembly.

Furthermore, this process is not at all compatible with the sputteringprocess, especially magnetically enhanced sputtering and preferablyreactive sputtering in the presence of oxygen and/or nitrogen,especially because of the very different working pressures: at the timeof this invention, the ion sources operated at pressures 10 to 100 timeslower than the pressures used in the processes for sputtering,especially magnetically enhanced sputtering and preferably reactivesputtering in the presence of oxygen and/or nitrogen.

More recently, ion sources have been developed that are more compatiblewith processes for depositing thin films by sputtering, in particular bysolving the problem of convergence of the particle beams and byimproving the matching between the size and the geometry, on the onehand, of the cathode and, on the other hand, of the ion source. Thesesystems, known as “linear sources”, are described for example indocuments U.S. Pat. No. 6,214,183 or U.S. Pat. No. 6,454,910.

Document WO 02/46491 describes the use of a source of this type forproducing a functional silver oxide layer by sputtering using a silvertarget with bombardment by an oxygen ion beam. The ion beam is used todensify the silver material and convert it into a layer containingsilver oxide. As a result of the densification, the silver oxide layeris capable of absorbing and/or reflecting a significant amount of theUV.

The object of the present invention is to remedy the drawbacks of theprior art and to provide novel thin-film materials that can be used tocoat transparent substrates of the glass type, novel depositionprocesses and novel installations.

The invention relies on the fact that it is possible to depositthin-film layers made of a dielectric, especially an oxide and/ornitride, with exposure to an ion beam by controlling the conditions sothat the material of the final layer has a better degree ofcrystallization, much greater than the degree of crystallization of thematerial deposited conventionally, that is to say without subjecting thelayer to at least one ion beam.

In this regard, the subject of the invention is a substrate, especiallya glass substrate, as claimed in claim 1. The substrate according to theinvention is coated with at least one dielectric thin-film layerdeposited by sputtering, especially magnetically enhanced sputtering andpreferably reactive sputtering in the presence of oxygen and/ornitrogen, with exposure to at least one ion beam coming from an ionsource, and the deposited dielectric layer exposed to the ion beam iscrystallized.

The term “crystallized” is understood to mean that at least 30% of theconstituent material of the dielectric layer exposed to the ion beam iscrystallized and that the size of the crystallites can be detected byX-ray diffraction, i.e. they have a diameter of greater than a fewnanometers.

The ion beam used to implement the present invention is what is called a“high-energy” beam, typically having an energy ranging from aroundseveral hundred eV to several thousand eV.

Advantageously, the parameters are controlled in such a way that thedielectric layer deposited on the substrate by sputtering with exposureto the ion beam has a very low roughness.

The term “very low roughness” is understood to mean that the dielectriclayer exposed to the ion beam has a roughness at least 20%, andpreferably at least 50%, less than that of the same dielectric layer notexposed to the ion beam.

The dielectric layer exposed to the ion beam may thus have a roughnessof less than 0.1 nm for a thickness of 10 nm.

Advantageously, the parameters may also be controlled in such a way thatthe layer has an index very much less or very much greater than theindex of a layer deposited without an ion beam, but which may also beclose to the index of a layer deposited without an ion beam.

Within the meaning of the present description, the term “close” impliesan index that differs from the reference value by at most around 5%.

The invention also makes it possible to create an index gradient in thedeposited layer.

In a variant, said layer thus has an index gradient adjusted accordingto the parameters of the ion source.

Advantageously, for at least some of the dielectric materials that canbe deposited, whatever the index modification produced, the density ofthe dielectric layer deposited on the substrate by sputtering withexposure to the ion beam may be maintained with a similar or identicalvalue.

Within the meaning of the present description, a “similar” density valuediffers from the reference value by at most around 10%.

The invention applies in particular to the production of a dielectriclayer made of a metal oxide or silicon oxide, whether stoichiometric ornonstoichiometric, or made of a metal nitride or oxynitride or siliconnitride or oxynitride.

In particular, the dielectric layer may be made of an oxide of at leastone element taken from silicon, zinc, tantalum, titanium, tin, aluminum,zirconium, niobium, indium, cerium, and tungsten. Among mixed oxidesthat can be envisioned, mention may in particular be made of indium tinoxide (ITO).

The layer may be obtained from a cathode made of a doped metal, that isto say one containing a minor element: as an illustration, it is commonpractice to use cathodes made of zinc containing a minor proportion ofanother metal, such as aluminum or gallium. In the present description,the term “zinc oxide” is understood to mean a zinc oxide possiblycontaining a minor proportion of another metal. The same applies to theother oxides mentioned.

For example, a zinc oxide layer deposited according to the invention mayhave a degree of crystallinity of greater than 90% and especiallygreater than 95% and an RMS roughness of less than 1.5 nm and especiallyaround 1 nm.

This zinc oxide layer deposited according to the invention may have arefractive index that can be adjusted to a value of less than or equalto 1.95, especially around 1.35 to 1.95. Its density may be maintainedat a value close to 5.3 g/cm³ and especially at a value of around5.3±0.2 g/cm³, identical to the density of a ZnO layer deposited at lowpressure, which is around 5.3 g/cm³.

Zinc oxide layers having a refractive index adjusted to a value of lessthan 1.88 and similar to this value may be obtained by setting thesputtering conditions (especially the oxygen content of the atmosphere)so as to deviate slightly from the stoichiometry of the intended oxideso as to compensate for the impact of the ion bombardment.

The dielectric layer may also be made of silicon nitride or oxynitride.Such nitride dielectric layers may be obtained by setting the sputteringconditions (especially the nitrogen content of the atmosphere) so as todeviate slightly from the stoichiometry of the intended nitride, so asto compensate for the impact of the ion bombardment.

In general, the ion beam has the effect of improving the mechanicalproperties of the dielectric layer.

As a result of the ion bombardment, quantities of one or more bombardedspecies are introduced into the layer, in a proportion that depends onthe nature of the gas mixture at the source and on thesource/cathode/substrate configuration. As an illustration, a layerdeposited under bombardment by an argon ion beam may include argon witha content of around 0.2 to 0.6 at %, especially about 0.45 at %.

Generating the ion beam via an ion source that uses soft iron cathodesor cathodes of any other material, especially paramagnetic material,which are eroded during the process, may be responsible for the presenceof traces of iron in the deposited layer. It has been confirmed thatiron present with a content of less than 3 at % or less is acceptable asit does not degrade the properties, especially optical or electricalproperties, of the layer. Advantageously, the deposition parameters(especially the substrate transport speed) are adjusted so as to have aniron content of less than 1 at %.

By preserving the usual optical properties, it is very easy toincorporate the dielectric layers thus obtained into multilayers knownfor manufacturing what are called “functional” glazing assemblies, inparticular using a silver-based metal functional layer.

Specific multilayers may be designed that incorporate a dielectric ofindex adjusted to a different value from the standard value.

Thus, the subject of the invention is a substrate coated with amultilayer in which a silver layer is deposited on top of saiddielectric layer exposed to the ion beam. Another dielectric layer maythen be deposited on top of this silver layer.

This configuration proves to be particularly advantageous when the lowerdielectric layer is based on zinc oxide and/or tin oxide as they giverise to particularly well oriented growth of the silver layer on theoxide layer, with improved final properties. It is known that thepresence of a zinc oxide layer beneath the silver has an appreciableinfluence on the quality of said silver layer. The formation of thesilver layer on the zinc oxide layer deposited according to theinvention results in a quite remarkable improvement.

In fact it is observed that the silver layer thus formed is bettercrystallized with an increase of 15 to 40% in the crystalline phase(diffraction from (111) planes) compared with the amorphous phase.

In this regard, the subject of the invention is also a process accordingto the invention for improving the crystallization of a silver layerdeposited on a dielectric layer, especially on a dielectric layer basedon zinc oxide, in which said dielectric layer is deposited on thesubstrate by sputtering, especially magnetically enhanced sputtering andpreferably reactive sputtering in the presence of oxygen and/ornitrogen, with exposure to at least one ion beam, preferably coming froma linear source. According to this process, at least one functionallayer, especially one based on silver, is deposited on said dielectriclayer and said functional layer undergoes a crystallization step. Thesize of the crystallites of the silver layer can therefore be increasedby around 15 to 40%, especially 30 to 40% (diffraction from (111)planes).

This is manifested by a reduction in the resistivity of the silver(which is directly related to the energy emissivity properties) or areduction in the surface resistance R_(□) by at least 10%, for the samesilver thickness, with an R_(□) value of less than 6 Ω/□, or even lessthan 2.1 Ω/□, especially around 1.9 Ω/□.

These substrates are thus particularly advantageous for producinglow-emissivity or solar-controlled glazing assemblies, or elsetranslucent elements with a high electrical conductivity, such as thescreens for electromagnetic shielding of plasma display devices.

In these substrates, another dielectric layer may be placed on top ofthe silver layer. It may be chosen based on the abovementioned oxides ornitrides or oxynitrides. The other layer itself may or may not bedeposited with exposure to an ion beam.

The multilayer may include at least two silver layers or even three orfour silver layers.

Examples of multilayers that can be produced according to the inventioncomprise the following sequences of layers:

ZnO ^((i))/Ag/oxide such as ZnO

Si₃N₄/ZnO ^((i))/Ag/oxide such as ZnO

Si₃N₄/ZnO ^((i))/Ag/Si₃N₄/(optionally an oxide)

Si₃N₄/ZnO ^((i))/Ag/Si₃N₄/ZnO ^((i))/Ag/Si₃N₄

Si₃N₄/ZnO ^((i))/Ag/Si₃N₄/ZnO ^((i))/Ag/Si₃N₄/(oxide)

where ^((i)) indicates that the layer is exposed to the ion beam andwhere a blocking metal layer may be inserted above and/or below at leastone silver layer.

The substrate used could also be made of a plastic, especially atransparent plastic.

The subject of the invention is also a process for manufacturing asubstrate as described above, i.e. a process for depositing amultilayer, in which at least one dielectric layer is deposited on thesubstrate by sputtering, especially magnetically enhanced sputtering andpreferably reactive sputtering in the presence of oxygen and/ornitrogen, in a sputtering chamber, with exposure to at least one ionbeam coming from an ion source. In the process according to theinvention, the ion beam is created from a linear source and therefractive index of said dielectric layer exposed to the ion beam may beadjusted according to the parameters of the ion source.

The refractive index of the dielectric layer exposed to the ion beam maybe decreased or increased relative to the index of this layer depositedwithout an ion beam.

Advantageously, for at least some of the dielectric materials to bedeposited, whatever the index modification produced, the density of thedielectric layer deposited on the substrate by sputtering with exposureto the ion beam is maintained.

Exposure to the ion beam takes place in the sputtering chambersimultaneously with and/or sequentially after the deposition of thelayer by sputtering.

The expression “simultaneously with” is understood to mean that theconstituent material of the dielectric thin-film layer is subjected tothe effects of the ion beam while it is yet to be completely deposited,that is to say that it has not yet reached its final thickness.

The term “sequentially after” is understood to mean that the constituentmaterial of the dielectric thin-film layer is subjected to the effectsof the ion beam when the layer has been completely deposited, that is tosay after it has reached its final thickness.

In the variant with exposure simultaneously with deposition, theposition of the ion source(s) is preferably optimized so that themaximum density of sputtered particles coming from the target isjuxtaposed with the ion beam(s).

Preferably, to produce an oxide-based dielectric layer, an oxygen ionbeam is created with an atmosphere containing very largely oxygen,especially 100% oxygen, at the ion source, whereas the atmosphere at thesputtering cathode is preferably composed of 100% argon.

In this variant, exposure to the ion beam takes place simultaneouslywith the deposition of the layer by sputtering. For this purpose, it isunnecessary to limit the ion energy as in the prior art; on thecontrary, an ion beam with an energy between 200 and 2000 eV or evenbetween 500 and 5000 eV, especially between 500 and 3000 eV, isadvantageously created.

The ion beam may be directed onto the substrate and/or onto thesputtering cathode, especially along a direction or at a non-zero anglewith the surface of the substrate and/or of the cathode respectively,such that the ion beam juxtaposes with the flux of neutral speciesejected from the target by sputtering.

This angle may be around 10 to 80° relative to the normal to thesubstrate, measured for example vertically in line with the center ofthe cathode, and vertically in line with the axis of the cathode when itis cylindrical.

In the case of direct flux on the target, the ion beam coming from thesource juxtaposes with the “racetrack” of the target created by thesputtering, that is to say the centers of the two beams, coming from thecathode and from the ion source respectively, meet at the surface of thesubstrate.

Advantageously, the ion beam may also be used outside the racetrack anddirected toward the cathode, in order to increase the degree of use ofthe target (ablation). The ion beam can therefore be directed onto thesputtering cathode at an angle of ±10 to 80° relative to the normal tothe substrate passing through the center of the cathode, and especiallythrough the axis of the cathode when it is cylindrical.

The source/substrate distance, in a sequential or simultaneousconfiguration, is from 5 to 25 cm, preferably 10±5 cm.

The ion source may be positioned before or after the sputtering cathodealong the direction in which the substrate runs (i.e. the angle betweenthe ion source and the cathode or the substrate is respectively negativeor positive relative to the normal to the substrate passing through thecenter of the cathode).

In a variant of the invention, an ion beam is created in the sputteringchamber using a linear ion source simultaneously with the deposition ofthe layer by sputtering, and then the deposited layer undergoes anadditional treatment with at least one other ion beam.

The present invention will be more clearly understood on reading thedetailed description below of illustrative but non-limiting examples andfrom FIG. 1 appended hereto, which illustrates a longitudinal sectionalview of an installation according to the invention.

To manufacture “functional” glazing assemblies (solar-controlledglazing, low-emissivity glazing, heated windows, etc.), it is usualpractice to deposit a thin-film multilayer comprising at least onefunctional layer on a substrate.

When this functional layer (or these functional layers) is (or are)especially based on silver, it is necessary to deposit a silver layer(thickness between 8 and 15 nm) whose normal emissivity and/orelectronic resistivity are minimal.

To do this, it is known that the silver layer must be deposited on anoxide sublayer which is:

(i) made of perfectly crystallized zinc (wurtzite phase) with apreferred orientation formed by the basal planes ((0002) planes)parallel to the substrate; and

(ii) perfectly smooth (minimal roughness).

The current technical solutions for depositing the zinc oxide do notallow both these characteristics to be obtained.

For example:

the solutions for crystallizing zinc oxide (by heating the substrate,increasing the cathode power, increasing the thickness and increasingthe oxygen content) result in an increase in the roughness of the layer,which leads to an appreciable degradation in the performance of thesilver layer deposited on top; and

the solutions for depositing a zinc oxide which is smooth or has a lowroughness (low-pressure deposition, deposition on a very smallthickness) result in partial amorphization of the silver layer, whichimpairs the quality of the heteroepitaxial growth of the silver on theZnO.

Within the context of the invention, it has been observed, surprisingly,that the deposition in particular of zinc oxide, but also of many otherdielectrics, assisted by an ion beam coming from a linear source makesit possible, under certain conditions, to deposit a highly crystallizedlayer with an extremely low roughness. This considerably improves thequality of the epitaxially grown silver layer on the subjacentdielectric and therefore both the optical and mechanical properties ofthe multilayers.

CONTROL EXAMPLE 1

In this example, a zinc oxide layer 40 nm in thickness was applied to aglass substrate using an installation (10) illustrated in FIG. 1.

The deposition installation comprised a vacuum sputtering chamber (2)through which the substrate (1) ran along conveying means (notillustrated here), along the direction and in the sense illustrated bythe arrow F.

The installation (2) included a magnetically enhanced sputtering system(5). This system comprised at least one cylindrical rotating cathode(but it could also have been a flat cathode), extending approximatelyover the entire width of the substrate, the axis of the cathode beingplaced approximately parallel to the substrate. This sputtering system(5) was placed at a height H5 of 265 mm above the substrate.

The material extracted from the cathode of the sputtering system wasdirected onto the substrate approximately as a beam (6).

The installation (2) also included a linear ion source (4) emitting anion beam (3), which also extended approximately over the entire width ofthe substrate. This linear ion source (4) was positioned at a distanceL4 of 170 mm from the cathode axis, in front of the cathode with regardto the direction in which the substrate runs, at a height H4 of 120 mmabove the substrate.

The ion beam (3) was directed at an angle A relative to the vertical tothe substrate passing through the axis of the cathode.

This deposition was carried out using a known sputtering technique onthe substrate (1) running through a sputtering chamber (2) past arotating cathode, based on Zn containing about 2% by weight of aluminumin an atmosphere containing argon and oxygen. The run speed was at least1 m/min.

The deposition conditions given in Table 1a below were adapted so as tocreate a slightly substoichiometric zinc oxide layer with an index of1.88 (whereas a stoichiometric ZnO layer has an index of 1.93-1.95).

This layer was analyzed by X-ray reflectometry in order to determine itsdensity and thickness, and by X-ray diffraction in order to determineits crystallinity. The spectrum revealed a peak at 2θ=34° typical of(0002) ZnO. The size of the crystallites was deduced from thediffraction spectrum using the conventional Scherrer formula and usingthe fundamental parameters.

The light transmission through the substrate, the light reflection fromthe substrate and the resistance per square were also measured. Themeasured values are given in Table 1b below.

EXAMPLE 1

In this example, a zinc oxide layer 40 nm in thickness was appliedaccording to the invention to a glass substrate.

This deposition was carried out by sputtering onto the substrate, whichran through the same sputtering chamber as in Control Example 1, in anatmosphere at the sputtering cathode containing only argon. A linear ionsource placed in the sputtering chamber was used to create,simultaneously with the sputtering, an ion beam using an atmosphere atthe source composed of 100% oxygen. The source was inclined so as todirect the beam onto the substrate at an angle of 30°.

The modified deposition conditions made it possible to produce a zincoxide layer having an index of 1.88, the density of which was identicalto that of the control material.

The optical properties were barely affected by exposure to the ion beam.

The X-ray diffraction spectrum revealed a very intense ZnO (0002) peakshowing, for constant ZnO thickness, an increase in the amount of ZnOthat crystallized and/or a more pronounced orientation.

An iron constant of less than 1 at % was measured by SIMS.

Rutherford backscattering spectroscopy measurements showed that the ZnOlayer contained 0.45 at % argon. TABLE 1a Sputtering Ion Source PressurePower Ar O₂ Energy Ar O₂ Units μbar kW sccm sccm eV sccm sccm Cont. Ex.1 0.8 3.0 80 70 — — — Ex. 1 0.9 3.0 100 0 2000 0 80

TABLE 1b Properties ZnO Crystallite Density Index T_(L) R_(L) R_(□) Size(nm) Units g/cm³ % % Ω/□ Scherrer Fund. Param. Cont. 5.30 1.88 83.8 16.1∞ 17 15 Ex. 1 Ex. 1 5.30 1.54 88.9 9.8 ∞ 12 12

EXAMPLE 2

In this example, a glass substrate was coated with the followingmultilayer:

10 nm ZnO/19.5 nm Ag/10 nm ZnO,

where the lower zinc oxide layer was obtained as in Example 1 withexposure to an ion beam.

As in Example 1, the lower layer was produced by adapting the residencetime of the substrate in the chamber in order to reduce the thickness ofthe oxide layer to 10 nm.

The substrate was then made to run past a silver cathode in anatmosphere composed of 100% argon and then once again past a zinccathode in an argon/oxygen atmosphere under the conditions of ControlExample 1.

This multilayer was analyzed by X-ray diffraction in order to determineits state of crystallization. The spectrum revealed a peak at 2θ=34°typical of ZnO, and a peak at 2θ=38° typical of silver. The size of thesilver crystallites was determined from the diffraction spectrum usingthe conventional Scherrer formula and using the fundamental parameters.

The light transmission through the substrate, the light reflection fromthe substrate and the surface resistance were also measured.

The results are given in Table 2 below.

These properties are compared with those of a Control Example 2 in whichthe lower zinc oxide layer was produced without exposure to the ionbeam.

The comparison reveals that the crystallization of the silver layer isconsiderably improved when the subjacent zinc oxide layer is producedwith exposure to the ion beam, this being manifested by a lower surfaceresistance, i.e. an improved conductivity. TABLE 2 Properties AgCrystallite T_(L) R_(L) R_(□) Size (nm) Units % % Ω/□ Scherrer Fund.Param. Cont. Ex. 2 52.3 45.5 2.07 15.7 15.3 Ex. 2 58.6 40.7 1.86 17.417.6

CONTROL EXAMPLE 3

In this example, the following multilayer was produced on a glasssubstrate: Substrate SnO₂ TiO₂ ZnO Ag NiCr SnO₂ 15 8 8 10 0.6 30in which the lower zinc oxide layer was obtained as in Example 1 withexposure to an ion beam.

The zinc oxide layer was produced as in Example 1 by adapting theresidence time of the substrate in the chamber in order to reduce thethickness of the oxide layer to 8 nm.

Next, the substrate was made to run past a silver cathode in anatmosphere composed of 100% argon.

The optical and performance properties of Control Example 3 as singleglazing (SG) and as double glazing (4/15/4 DG with the internal cavitycomposed of 90% Ar) are given in Table 3 below.

EXAMPLE 3

The same deposition conditions as those of Control Example 3 were used,except that a linear ion source was placed in the sputtering chamber andwas used to create, simultaneously with the sputtering, an ion beamduring production of the zinc-oxide-based layer, with an atmosphere atthe source composed of 100% oxygen. The source was inclined so as todirect the beam onto the substrate at an angle of 30° and was positionedat a distance of about 14 cm from the substrate.

These modified deposition conditions made it possible to produce a zincoxide layer having an index substantially identical to that of thecontrol layer.

The optical and performance properties of Example 3 as single glazing(SG) and as double glazing (4/15/4 DG, the internal cavity of which wascomposed of 90% Ar) are also given in Table 3 below. TABLE 3 T_(L) R_(L)ε_(n) R_(□) (%) (%) a* b* (%) (Ω/□) Con. Ex. 3 SG 86 4.4 3.7 −7.8 Con.Ex. 3 DG 77.4 11.6 0.7 −3.8 5.5 5 Ex. 3 SG 86.5 4.2 3.2 −7.7 Ex. 3 DG77.7 11.5 0.5 −3.8 5 4.5

As may be seen, the optical properties are barely affected by exposureto the ion beam, but the thermal properties are substantially improved,since a gain of 10% is obtained in terms of resistance per square(R_(□)) and in normal emissivity (ε_(n)).

CONTROL EXAMPLE 4

A multilayer having the following layer thickness (in nanometers) wasproduced on a glass substrate, corresponding to the multilayer sold bySaint-Gobain Glass France under the brand name PLANISTAR: Substrate SnO₂ZnO Ag Ti ZnO Si₃N₄ ZnO Ag Ti ZnO Si₃N₄ 25 15 9.0 1 15 56 15 13.5 1 1521

The optical and performance properties of Control Example 4 as doubleglazing (4/15/4, with the internal cavity composed of 90% Ar) are givenin Table 4 below.

EXAMPLE 4

A multilayer having the same thicknesses as Control Example 4 wasproduced under the same conditions as those of Control Example 4, exceptthat a linear ion source was placed in the sputtering chamber and usedto create, simultaneously with the sputtering, an ion beam duringproduction of each zinc-oxide-based layer directly subjacent to eachsilver-based functional layer.

The atmosphere at the source was composed of 100% oxygen. The source wasinclined so as to direct the beam onto the substrate at an angle of 30°and was positioned at a distance of about 14 cm from the substrate. Theenergy of the ion beam was, for each pass, around 1000 eV. The pressureinside the chamber was 0.1 pbar during the first pass and 4.3 μbarduring the second pass, for a target power of 5.5 kW during the firstpass and 10 kW during the second pass.

These modified deposition conditions made it possible to produce a zincoxide layer having an index substantially identical to that of thecontrol layer.

The optical and performance properties of Example 4 as double glazing(4/15/4 the internal cavity of which was composed of 90% Ar) are alsogiven in Table 4 below.

As may be seen, the optical properties are barely affected by exposureto the ion beam, but the thermal properties are greatly improved, sinceagain a gain of about 10% is obtained in terms of resistance per square(R_(□)). TABLE 4 T_(L) λ_(d) p_(e) R_(ext) SF U R_(□) (%) (nm) (%) (%)L* a* b* (CEN) (W/m² · K) (Ω/□) Con. Ex. 4 71.8 553 2.6 12.0 41.2 −2.3−1.7 42 1.17 2.7 Ex. 4 72.7 540 1.9 11.4 40.2 −2.7 −1.2 42 1.12 2.4

EXAMPLE 5

The following multilayer was deposited : glass/Si₃N₄/ZnO (25 nm)/Ag (9nm) and then the crystallographic characteristics of the zinc oxide andthe electrical properties of the silver layer were measured. Inaddition, the RMS roughness of a ZnO(25 nm) glass not coated with silverand produced under the same conditions as previously was evaluated. Theangle of inclination A of the ion source relative to the substrate was30°. The measured values are given in Table 5 below. TABLE 5 Area of theRMS roughness ZnO (nm) Resistance per (0002) Bragg measured by AFMsquare of a 9 nm peak (a.u.) (25 nm thickness) thick silver film ZnOwithout ion 0 1.8 8.2 assistance U = 1500 V 78 1.4 7.0 U = 3000 V 19 1.46.8

It may therefore be observed, surprisingly, that deposition of ZnOassisted by an ion beam makes it possible in the above multilayer toreduce the roughness of the layer thus deposited.

EXAMPLE 6

TiO₂ monolayers were deposited on the glass with and without assistanceby an ion source and then the roughness was measured by simulation ofthe optical properties (dispersion relationship) and by X-rayreflectometry. The angle of inclination A of the ion source relative tothe substrate was 20°. The measured values are given in Table 6 below.TABLE 6 Optical Roughness X-ray RMS Roughness (nm) (nm) TiO₂ without ionassistance 1.7 1.5 U = 1000 V 0 0.5 U = 2000 V 0 0.7

The present invention has been described in the foregoing by way ofexample. Of course, a person skilled in the art would be capable ofproducing various alternative embodiments of the invention withoutthereby departing from the scope of the patent as defined by the claims.

1. A substrate which may be a glass substrate, coated with at least onedielectric thin-film layer deposited by sputtering, which may bemagnetically enhanced sputtering or reactive sputtering in the presenceof oxygen and/or nitrogen, with exposure to at least one ion beam comingfrom an ion source, wherein said dielectric layer exposed to the ionbeam is crystallized.
 2. The substrate as claimed in claim 1, whereinsaid dielectric layer deposited on the substrate by sputtering withexposure to the ion beam has a very low roughness.
 3. The substrate asclaimed in claim 2, wherein the dielectric layer exposed to the ion beamhas a roughness at least 20% less than that of the same dielectric layernot exposed to the ion beam.
 4. The substrate as claimed in claim 1,wherein said dielectric layer comprises a metal oxide or silicon oxide,which may be stoichiometric or nonstoichiometric, or comprises a metalnitride or oxynitride or silicon nitride or oxynitride.
 5. The substrateas claimed in claim 1, wherein said dielectric layer comprises an oxideof at least one element selected from the group consisting of silicon,zinc, tantalum, titanium, tin, aluminum, zirconium, niobium, indium,cerium, and tungsten.
 6. The substrate as claimed in claim 5, whereinthe layer comprises zinc oxide and has a refractive index of less thanor equal to 1.95.
 7. The substrate as claimed in claim 5, wherein thelayer comprises zinc oxide and has a degree of crystallinity of greaterthan
 90. 8. The substrate as claimed in claim 1, wherein said dielectriclayer comprises silicon nitride or oxynitride.
 9. The substrate asclaimed in claim 1, wherein said layer has an argon content of around0.2 to 0.6 at %.
 10. The substrate as claimed in claim 1, wherein saidlayer has an iron content of less than or equal to 3 at %.
 11. Thesubstrate as claimed in claim 1, wherein said substrate is coated with amultilayer in which a silver layer is placed on top of said dielectriclayer exposed to the ion beam.
 12. The substrate as claimed in claim 11,wherein another dielectric layer is placed on top of the silver layer.13. The substrate as claimed in claim 11, wherein the multilayerincludes at least two silver layers.
 14. The substrate as claimed inclaim 11, wherein said substrate has a surface resistance R_(□) of lessthan 6 Ω/□.
 15. A glazing assembly which may be a double-glazing orlaminated glazing assembly, comprising at least one substrate as claimedin claim
 1. 16. A process for deposition on a substrate, in which atleast one dielectric thin-film layer is deposited on the substrate bysputtering, which may be magnetically enhanced sputtering or reactivesputtering in the presence of oxygen and/or nitrogen, in a sputteringchamber, with exposure to at least one ion beam coming from an ionsource, wherein an ion beam is created in the sputtering chamber and inthat said dielectric layer exposed to the ion beam undergoes acrystallization step.
 17. The process as claimed in claim 16, wherein anoxygen ion beam is created.
 18. The process as claimed in claim 16,wherein an ion beam is created with an energy of between 200 and 2000eV.
 19. The process as claimed in claim 16, wherein said dielectriclayer deposited on the substrate by sputtering with exposure to the ionbeam has a very low roughness.
 20. The process as claimed in claim 16,wherein exposure to an ion beam takes place simultaneously with thedeposition of the layer by sputtering.
 21. The process as claimed inclaim 16, wherein exposure to an ion beam takes place sequentially afterthe layer has been deposited by sputtering.
 22. The process as claimedin claim 16, wherein an ion beam is directed onto the substrate, whichmay be along a direction making a nonzero angle with the surface of thesubstrate, or along a direction making an angle of 10 to 80° with thesurface of the substrate.
 23. The process as claimed in claim 16,wherein an ion beam is directed onto at least one cathode, which may bealong a direction making a nonzero angle with the surface of thecathode, or along a direction making an angle of 10 to 80° with thesurface of this cathode.
 24. The process as claimed in claim 16, whereinthe ion beam is created from a linear source.
 25. The process as claimedin claim 16, wherein at least one functional layer, which may be onebased on silver, is deposited on said dielectric layer and in that saidfunctional layer undergoes a crystallization step.
 26. The process asclaimed in claim 25, wherein the at least one functional layer is basedon silver and the size of the crystallites of the silver layer isincreased by around 30 to 40%.
 27. The process as claimed in claim 16,wherein the dielectric layer is based on zinc oxide.
 28. The process asclaimed in claim 16, wherein an ion beam is created in the sputteringchamber from a linear ion source simultaneously with the deposition ofthe layer by sputtering and in that the deposited layer then undergoesan additional treatment with at least one other ion beam.
 29. Aninstallation for deposition on a substrate, which may be a glasssubstrate, for the manufacture of the substrate as claimed in claim 1,which includes a sputtering chamber in which at least one dielectricthin-film layer is deposited on the substrate by sputtering, which maybe magnetically enhanced sputtering or reactive sputtering in thepresence of oxygen and/or nitrogen, with exposure to at least one ionbeam, wherein the installation includes, in the sputtering chamber atleast one linear ion source capable of creating at least one ion beam.30. The installation as claimed in claim 29, wherein a linear ion sourceis placed so as to direct an ion beam onto the substrate, which may bealong a direction making a nonzero angle, or an angle of 10 to 80°, withthe surface of the substrate.
 31. The installation as claimed in claim29, wherein a linear ion source is placed so as to direct an ion beamonto at least one cathode, which may be along a direction making anonzero angle, or an angle of 10 to 80°, with the surface of thiscathode.